This article deals with changes in political boundaries, border regimes and border policies that have taken place in the area between the Baltic and the Mediterranean, which corresponds in the broadest sense with the term ‘Europe-in-between’. An important generator of problems here has been the multi-ethnic composition of the population, a source of diffuse political processes often even giving rise to conflict. Border policies have served as indicators of the relationships pertaining between countries, though they have an even broader exponent relating EU policies and peacekeeping missions, among other things, and thus offering nothing less than a laboratory for geopolitics both old and new. In the three parts present here, the first represents a short theoretical discussion concerning national systems, while the second offers an empirical analysis of border changes and policies in the area stretching from Kaliningrad to the Bosphorus and Trieste. Finally, a third, synthetic, part discusses recent challenges to border policies in the area in question posed by processes of European integration, as set against the new security paradigms of our era. Particular emphasis is placed on strong immigration pressure, pan-Turkish strategic aspirations, the Balkan area and its policies and the relationship between the EU and Russia.